1. Field of the Invention
The present general inventive concept relates to a cleaning apparatus usable with an image forming apparatus and an image forming apparatus including the same, and more particularly, to a cleaning apparatus to collect waste toner remaining on a photosensitive body after being transferred, and an image forming apparatus including the same.
2. Description of the Related Art
In general, an image forming apparatus, such as a laser printer or a copy machine, forms images while printing on sheets that are loaded in a paper feeding cassette, which is detachably installed in a main body of the image forming apparatus. An uppermost one of the sheets that are loaded in the paper feeding cassette is sequentially picked up by a pickup unit and moved to an image forming unit within the image forming apparatus.
FIG. 1 is a sectional view illustrating a conventional image forming apparatus, FIG. 2 is a sectional view illustrating a conventional cleaning apparatus of the conventional image forming apparatus of FIG. 1, FIG. 3 is a perspective view illustrating a cleaning blade of the conventional cleaning apparatus of FIG. 2, and FIG. 4 is a sectional view illustrating a waste toner reservoir unit of the conventional cleaning apparatus taken along line A-A of FIG. 2.
Referring to FIG. 1, a conventional image forming apparatus 1 is an electrophotographic image forming apparatus in which an electrostatic latent image formed on an external surface of a photosensitive body 15 is developed into a visible image by supplying toner, which is a developing agent, to the electrostatic latent image. The visible image is then transferred to a printing paper P and is then fused to obtain a desired printed image. In the conventional image forming apparatus 1, the printing paper P is moved from a lower portion to an upper portion thereof along a C-shaped path. The conventional image forming apparatus 1 includes a conventional cleaning apparatus 5, a transferring roller 25, a fixing unit 30, a laser scanning unit (LSU) 70, and a pick-up unit 50 including a pickup roller 55, which picks up the printing paper P
The LSU 70 scans light that corresponds to image information to be printed onto the photosensitive body 15, which is described below, according to a computer signal to form the electrostatic latent image on the external surface of the photosensitive body 15.
Referring to FIG. 2, the conventional cleaning apparatus 5 includes a developing unit 10, the photosensitive body 15, and a waste toner reservoir unit 80.
The developing unit 10 is a cartridge that is detachably installed in a main frame 2 of the conventional image forming apparatus 1 (see FIG. 1). The developing unit 10 includes a developing unit housing 11, a developing roller 17, a supplying roller 19, an agitator 21, and a toner layer regulating unit 18. In addition, a toner storing portion 12 to store toner (i.e., the developing agent) is provided in the developing unit housing 11 of the developing unit 10. The developing unit 10 is replaced when the toner contained in the toner storing portion 12 is fully consumed.
The toner contained in the toner storing portion 12 is coated on an external surface of the developing roller 17, which supplies the toner to the photosensitive body 15. The developing roller 17, which is coated with toner in a solid powder form, develops the electrostatic latent image into a toner image by supplying the toner to the electrostatic latent image formed on the photosensitive body 15. A developing bias voltage is applied to the developing roller 17 to supply the toner to the photosensitive body 15. The supplying roller 19 supplies the toner in the toner storing portion 12 to the developing roller 17 while rotating in a predetermined direction. The agitator 21 agitates the toner in the toner storing portion 12 at a predetermined speed to prevent caking of the toner and moves the toner in the toner storing portion 12 closer to the supplying roller 19. One end of the toner layer regulating unit 18 is fixed to the developing unit housing 11. The other end of the toner layer regulating unit 18 contacts the developing roller 17, regulates a height of toner adhering to the external surface of the developing roller 17, and charges the toner to a predetermined polarity by creating friction.
Referring to FIGS. 1 and 2, the photosensitive body 15 rotates in a predetermined direction and is installed such that a portion of the external surface thereof is exposed. The photosensitive body 15 is charged to a predetermined potential by a charging roller 13, which is described below. As described above, the electrostatic latent image that corresponds to an image to be printed is formed on the external surface of the photosensitive body 15 according to the light emitted by the LSU 70. An exposed portion of the external surface of the photosensitive body 15 faces the transferring roller 25.
A charge bias voltage is applied to the charging roller 13. The charging roller 13 then charges the photosensitive body 15 to a predetermined potential.
Referring to FIGS. 2 and 4, the waste toner reservoir unit 80 is installed above and displaced from a center of the photosensitive body 15 and includes a housing 90, a cleaning blade 82, an auger 83, and a storing portion 86 (See FIG. 4).
The housing 90 is machined into a bent shape and forms a body of the waste toner reservoir unit 80. Referring to FIGS. 2 and 3, the cleaning blade 82 is installed such that one edge thereof is attached to the housing 90 and the other edge thereof is installed along a lengthwise direction of the photosensitive body 15 to contact and push a portion of the photosensitive body 15 with a predetermined force such that waste toner 81 remaining on the photosensitive body 15 can be removed therefrom. Referring to FIG. 4, the auger 83 is installed in the waste toner reservoir unit 80 to rotate in a predetermined direction to convey the waste toner 81 that is removed from the photosensitive body 15 into the storing portion 86 (See FIG. 4) along the lengthwise direction of the photosensitive body 15. The storing portion 86 (See FIG. 4) is located at one end of the waste toner reservoir unit 80 and receives the waste toner 81 that is conveyed by the auger 83.
Referring to FIG. 1, the transferring roller 25 is installed to face a circumference of the photosensitive body 15 and applies a transfer bias voltage having a polarity opposite to the toner image developed on the photosensitive body 15 such that the toner image can be transferred to the paper P. The toner image is transferred to the paper P by the electrostatic force exerted between the photosensitive body 15 and the transferring roller 25.
The fixing unit 30 includes a heating roller 31 and a pressing roller 33 installed to face the heating roller 31. The fixing unit 30 fixes the toner image to the paper P by applying heat and pressure to the toner image. The heating roller 31, which is a heat source for permanently fixing the toner image, is installed to face the pressing roller 33 along the axial direction. The pressing roller 33, which is installed to face the heating roller 31, fixes the toner image to the paper P by applying a high pressure to the paper R An uncurling portion 34 flattens the paper P, which has a curled shape due to heat that is applied while passing through the fixing unit 30. A paper discharging roller 35 discharges the paper P to which the toner image has been fixed out of the conventional image forming apparatus 1. The paper P that is discharged out of the conventional image forming apparatus 1 is laid on a printed paper cassette 3.
The conventional image forming apparatus 1 includes a paper feeding cassette 51 receiving blank sheets of paper P disposed under the main frame 2. The paper feeding cassette 51 includes a knock-up plate 53 on which sheets of paper P are loaded, a shaft 54, which is positioned above a front end of the knock-up plate 53 when the paper feeding cassette 51 is coupled to the image forming apparatus 1. The shaft 54 is rotated by driving power applied thereto by a driving motor (not shown) installed in the conventional image forming apparatus 1. A pick-up roller 55 is coupled with the shaft 54 and is rotated accordingly. An elastic member 57 elastically biases the knock-up plate 53 toward the pick-up roller 55 such that a leading edge of the paper P loaded on the knock-up plate 53 contacts and is moved by the pick-up roller 55. The pick-up roller 55 picks up the sheets of paper P loaded on the knock-up plate 53 one by one and moves the sheets of paper P toward a paper aligning unit 40. A frictional pad 60 is provided between the knock-up plate 53 and the paper aligning unit 40 to prevent more than one sheet of paper P picked up by the pick-up roller 55 from being fed forward such that only the uppermost sheet of paper P on the knock-up plate 53 can be transferred toward the paper aligning unit 40. The paper aligning unit 40 aligns the paper P to pass between the photosensitive body 15 and the transferring roller 25 such that the toner image can be transferred to a desired position on the paper P.
Hereinafter, operations of the conventional cleaning apparatus 5 and the conventional image forming apparatus 1 including the conventional cleaning apparatus 5 will be described with reference to FIGS. 1 through 4.
The photosensitive body 15 is uniformly charged to the predetermined potential by the charge bias voltage applied to the charging roller 13. The laser scanning unit (LSU) 70 radiates light corresponding to the image information according to the computer signal onto the photosensitive body 15. A portion of the photosensitive body 15 scanned by the LSU 70 is selectively discharged, thereby resulting in a drop in the predetermined potential. An electrostatic latent image is formed due to this variation in potential.
The toner in the toner storing portion 12 is agitated by the agitator 21 and is supplied to the developing roller 17 to which the developing bias voltage has been applied by the supplying roller 19. The thickness of toner adhering to the circumference of the developing roller 17 is made thin and uniform by the toner layer regulating unit 18. The toner adhering to the developing roller 17 is charged due to the friction between the developing roller 17 and the toner layer regulating unit 18. The toner on the circumference of the developing roller 17 adheres to the electrostatic latent image formed on the circumference of the photosensitive body 15 so that the electrostatic latent image on the photosensitive body 15 is developed into the toner image.
The paper P is drawn from the paper feeding cassette 51 by the pick-up roller 55. The paper P is transferred forth and appropriately aligned by the paper aligning unit 40 and passes between the photosensitive body 15 and the transferring roller 25. When the transfer bias voltage is applied to the transferring roller 25, the toner image developed on the photosensitive body 15 is transferred to the paper P.
After the toner image is transferred to the paper P, the waste toner 81 remaining on the circumference of the photosensitive body 15 is removed by the cleaning blade 82, and the removed waste toner 81 is conveyed along the lengthwise direction of the photosensitive body 15 into the storing portion 86 by the auger 83.
The fixing unit 30 fixes the toner image to the paper P by applying heat and pressure to the toner image that is transferred to the paper P. The uncurling portion 34 flattens the paper P, which is curled while passing through the fixing unit 30. The paper P that is transferred through the uncurling portion 34 is discharged out of the conventional image forming apparatus 1 and is laid on the printed paper cassette 3.
In the conventional image forming apparatus 1 in which the paper P is moved from the lower portion to the upper portion along a C-shaped path as described above, many spatial limitations arise due to this structure. In particular, in the conventional image forming apparatus 1 including the conventional cleaning apparatus 5, a space for storing the waste toner 81 removed from the photosensitive body 15 is an important consideration.
In the conventional cleaning apparatus 5 described above, the space for storing the waste toner 81 (i.e., the storing portion 86 ) has to be reserved on a side of the waste toner reservoir unit 80, and the waste toner 81 removed from the photosensitive body 15 has to be transported to the space for storing the waste toner 81 using a separate transporting device (i.e., the auger 83 ). Due to the needs for a separate space for storing the waste toner 81 and the waste toner transporting device, the structure of the conventional image forming apparatus 1 is complicated and manufacturing costs increase. Furthermore, the housing 90 of the waste toner reservoir unit 80 is relatively weak because it is machined using a bending technique. In addition, since the housing 90 of the waste toner reservoir unit 80 is installed above and displaced from the center of the photosensitive body 15, upper surfaces of the photosensitive body 15 and the developing unit 10 are exposed and are likely to be deformed by external impact.